The invention relates to an arrangement for open-end friction spinning with two adjacently arranged rollers driven in the same rotational direction and forming a yarn forming wedge-shaped gap serving as a yarn formation region. At least one fiber inlet device is provided for guiding the single fibers to the wedge-shaped gap, which fiber inlet device includes a fiber feed channel directed toward the friction rollers and fiber feed opening means forming a distribution zone for the fibers being supplied. A yarn withdrawal device is provided for drawing off the produced yarn in the longitudinal direction of the wedge-shaped gap.
With a known arrangement or device of the above-mentioned kind disclosed in German Published Unexamined Application, (DE-OS) 29 43 063, an additional channel connects to the fiber feed channel in the area of its opening. Air is sucked off through the additional channel so that the opening of the fiber feed channel and thereby also the distribution zone for the fibers to be supplied, extends practically over the entire length of the wedge-shaped gap.
With another known arrangement or device disclosed in German Published Unexamined Application (DE-OS) 30 47 987, single fibers, so called wrapping fibers, are supplied from the fiber inlet device to the wedge-shaped gap formed by the two rollers whereby the same covers a fiber rove supplied in longitudinal direction of the wedge-shaped gap. The yarn being produced is drawn off in the longitudinal direction of the wedge-shaped gap by means of a pair of withrawal rollers. The actual yarn formation process is conducted in the area of the opening of the fiber feed channel, which means the so-called dispersion or distribution zone, in which the yarn being produced gradually increases its diameter. With the known arrangement a treatment zone connects to the distribution zone in the direction of the yarn withdrawal in which, for example, a straightening of the produced yarn is contemplated.
The invention is based upon the problem to so construct an arrangement or device of the kind mentioned above, that the yarn formation process is more controlled while an adjustment can be made to accommodate the differences in the fiber material to be processed and the predetermined desired yarn characteristics.
This problem is thereby solved in accordance with the invention by establishing the relative position of the distribution zone with respect to the rollers and/or its size dependent upon the length of the fibers of the fiber material to be processed and/or dependent upon the predetermined yarn characteristics of the yarn to be produced.
The invention utilizes the determination that especially the length of the distribution zone in the longitudinal direction of the wedge-shaped gap has an important influence upon the resultant yarn formation. In this area or region a thin extending yarn tip is first formed which enlarges itself in the yarn withdrawal direction to a yarn exhibiting the final yarn thickness. The length of the yarn tip is proportional to the length of the distribution zone. With a longer distribution zone one will obtain a lesser yarn volume since the core of the yarn is spun harder or tighter while the exterior fibers forming the yarn cover are less tightly twisted. If, however, the yarn tip gets too long based upon an extensive distribution zone, the danger of decoupling exists, which means stronger twisted thinning portions which are essentially produced by false drawing. A shorter dispersion zone leads to a greater yarn volume since the core of the yarn is twisted less tightly. With a yarn tip too short due to a too short distribution zone, however, the danger exists that short periodic inconsistency errors are the result and that the fibers are less well organized and arranged. By means of testing, one can determine the most favorable length of the fiber distribution zone dependent upon the desired yarn number, the yarn characteristic, and the fiber length of the material to be spun.
According to a further aspect of the invention, means are provided by which the relative positioning of the distribution zone with respect to the roller and/or its size is adjustable. It can therefore be provided to design these means at the spinning unit of an open-end friction spinning machine. It is, however, also contemplated by the invention to produce a test spinning sample with fiber material being produced on only a single unit, for example, a spin tester, in order to thereby optimize the relative positoning of the distribution zone and/or its size. Thereafter the machine is then equipped with correspondingly dimensioned fiber feed channels or partial sections of the same channels.
According to a further aspect of certain preferred embodiments of the invention it is provided that at least the part of the fiber feed channel opposite the friction rollers is designed as an independent, interchangeable structural element. An adjustment is thereby made possible without bothering the servicing person with adjustment tasks.
According to a further aspect of certain preferred embodiments of the invention it is provided that the fiber feed channel includes a seat for an insert which contains at least one channel wall and extends up to the fiber feed opening of the fiber feed channel. Especially if the insert comprises several channel walls, according to certain preferred embodiments the fiber transport guide path within the fiber feed channel can also be influenced by exchanging the insert, whereby the spinning quality is additionally increased.
According to certain embodiments of the invention it is provided that the part of the fiber feed channel containing the fiber feed opening is limited in longitudinal direction with respect to the wedge-shaped gap by means of an adjustable channel wall. With this embodiment very accurate adjustments can be made.
In a further embodiment of the invention it is provided that the fiber feed channel essentially arranged in the plane of the wedge-shaped gap and inclined in an angle thereto is provided with a section adjustably retained in its longitudinal direction and comprising the corresponding fiber feed openings to the friction rollers. The distance of the fiber feed opening to the wedge-shaped gap or the rollers is changed by adjusting the adjustable partial element, thereby changing the position of the distribution zone, and certainly also the length of the adjacent yarn treating zone. Additionally the subpressure of the suction device effective in the fiber feed channel is thereby also influenced so that the fiber tranpsort itself has an influence upon the fiber dispersion within the fiber feed channel.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.